Mr Justice Warby struck out parts of the Duchess of Sussex’s claim against Associated Newspapers, following a hearing last week.

The publisher of the Mail on Sunday has won the first High Court skirmish in the Duchess of Sussex’s claim against it over publication of a “private and confidential” letter to her estranged father.

Meghan is suing Associated Newspapers over five articles, two in the Mail on Sunday and three on MailOnline, which were published in February 2019 and reproduced parts of a handwritten letter she sent to Thomas Markle, 75, in August 2018.

A preliminary hearing, in which lawyers for the publisher asked for parts of the duchess’s case to be struck out, was held last week, with the judge sitting at the Royal Courts of Justice in London and lawyers and reporters attending remotely.

In a ruling on Friday, Mr Justice Warby struck out parts of Meghan’s claim against the publisher, including allegations that it acted “dishonestly” by leaving out certain passages of the letter.

The judge also struck out allegations that the publisher deliberately “stirred up” issues between Meghan and her father, and that it had an “agenda” of publishing intrusive or offensive stories about her.

Mr Justice Warby said those allegations should not form part of her case at this stage, because they were “irrelevant” to her claim for misuse of private information, copyright infringement and breach of the Data Protection Act.

However, he said those parts of her case may be revived at a later stage, if they are put on a proper legal basis.

The judge said: “Some of the allegations are struck out as irrelevant to the purpose for which they are pleaded.

“Some are struck out on the further or alternative ground that they are inadequately detailed.

“I have also acted so as to confine the case to what is reasonably necessary and proportionate for the purpose of doing justice between these parties.

“I do not consider that the allegations struck out on that basis go to the ‘heart’ of the case, which at its core concerns the publication of five articles disclosing the words of, and information drawn from, the letter written by the claimant to her father in August 2018.

“Some aspects of the case that I have struck out at this stage may be revived if they are put in proper form.”

The duchess is seeking damages from Associated Newspapers for alleged misuse of private information, copyright infringement and breach of the Data Protection Act.

Meghan has previously said any damages she may be awarded if she wins her case will be donated to an anti-bullying charity.

Associated Newspapers wholly denies the allegations, particularly the claim that the letter was edited in any way that changed its meaning, and says it will hotly contest the case.

It is understood that the Duke of Sussex and Meghan listened online to the parts of last week’s hearing conducted by her lawyers.

Sections of the letter were published in the newspaper and online in February last year, and it was announced in October that the duchess would be taking legal action.

The headline on the main article read: “Revealed: The letter showing true tragedy of Meghan’s rift with a father she says has ‘broken her heart into a million pieces’”.

No date has been set for any further hearing in the case and it is not known when a full trial of the issues is expected to take place.

In a statement issued after the judgment, a spokesperson for Schillings, which is representing Meghan, said the ruling “makes very clear that the core elements of this case do not change and will continue to move forward.

“The duchess’ rights were violated; the legal boundaries around privacy were crossed,” the spokesperson said.

“As part of this process, the extremes to which The Mail On Sunday used distortive, manipulative, and dishonest tactics to target the Duchess of Sussex have been put on full display.”

The spokesperson added that they are “surprised” that the judge’s ruling “suggests that dishonest behaviour is not relevant”.

“We feel honesty and integrity are at the core of what matters; or as it relates to the Mail on Sunday and Associated Newspapers, their lack thereof.

“Nonetheless, we respect the Judge’s decision as the strong case against Associated will continue to focus on the issue of a private, intimate and hand-written letter from a daughter to her father that was published by the Mail on Sunday.”